Added indication for converting ICD codes with positive combination flags.
Added fast implementation of the mapping tools developed by AHRQ for
translating ICD-9 (resp. ICD-10) codes to ICD-10 (resp. ICD-9) codes based
on the General Equivalence Mappings (GEM) from the Centers for Medicare and
Medicaid Services (CMS).
The first version of package that provides functions for mapping ICD-9 codes
to the AHRQ comorbidity measures.